There is a hybrid construction machine in which a hydraulic pump and a motor generator are connected to a diesel engine such that a hydraulic actuator is driven by the hydraulic pump while a power storage device is charged by a power generation action of the motor generator and the diesel engine is assisted by an electric action of the motor generator.
In such a hybrid construction machine as described above, a diesel particulate collection filter (hereinafter referred to simply as “filter”) is provided as an exhaust gas post-processing device for collecting PM (diesel particle) included in exhaust gas of the diesel engine. If an amount of PM greater than a predetermined level is deposited on the filter, then this causes clogging. Therefore, a process called “filter regeneration” for increasing the catalyst temperature in the filter to a temperature equal to or higher than a predetermined value and maintaining the temperature to burn and remove the deposited PM is performed.
There is also a hybrid type excavator in which, in order to improve the energy efficiency by effectively utilizing the engine output power also when the filter regeneration process is performed, when the stored amount of electricity in a power storage device is smaller than a threshold level, filter regeneration is performed in a state in which the load applied to the diesel engine is increased by a motor generator (for example, refer to Patent Document 1).
Further, there is a parallel hybrid automobile which changes over its traveling mode between motor traveling by electricity and engine traveling by fossil fuel in which, in order to prevent degradation of the purification performance of the catalyst in an engine exhaust path caused by a long time motor traveling, after traveling by the motor is performed for a long time, the traveling is changed over to a special traveling mode in which the hybrid automobile travels only by the engine to increase the temperature of the catalyst rapidly thereby to prevent increase of exhaustion of hazardous materials (for example, refer to Patent Document 2).
Further, there is a warming method for a hybrid type construction machine which is characterized in that, in order to effectively warm an accumulator without using a heating device under a low-temperature environment, when the temperature of the accumulator is lower than a temperature set in advance, the engine is rendered operative to perform warming and the motor generator is rendered operative to charge and discharge the accumulator to cause the accumulator to generate heat (for example, refer to Patent Document 3).